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SUMMARY:Imaging Earth’s interior with adjoint tomography based on 3D glo
 bal seismic wave simulations - Ebru Bozdag (Colorado School of Mines)
DTSTART:20230131T094500Z
DTEND:20230131T103000Z
UID:TALK194530@talks.cam.ac.uk
DESCRIPTION:Ebru Bozdag(1)\, Ridvan Orsvuran(1)\, Armando Espindola Carman
 o(2)\, Daniel Peter(2)\n(1)Colorado School of Mines\, (2) King Abdullah Un
 iversity Science and Technology\nSeismic waves generated by passive source
 s such as earthquakes are our primary tools for probing Earth's interior. 
 Improving the resolution of the seismic models of deep Earth's interior is
  crucial to understand the dynamics of the mantle (from ~30 km to 2900 km 
 depth) and the core (from 2900 km to 6371 km depth)\, which directly contr
 ol\, for instance\, the shape of the surface through plate tectonics and v
 olcanic activity\, and the generation of Earth's magnetic field\, respecti
 vely. The improved seismic models are also essential for seismic hazard as
 sessment and better modeling of earthquakes and nuclear explosions.\nAdvan
 ces in computational power and the availability of high-quality seismic da
 ta from dense seismic networks and emerging instruments offer excellent op
 portunities to refine our understanding of multi-scale Earth's structure a
 nd dynamics from surface to the core. We are at a stage where we need to t
 ake the full complexity of seismic wave propagation into account and avoid
  commonly used approximations to the wave equation and corrections in seis
 mic tomography. Imaging Earth's interior globally with full-waveform inver
 sion has been one of the most challenging projects in seismology in terms 
 of computational requirements and available data that can potentially be a
 ssimilated in seismic inversions. The first-generation global adjoint mode
 ls take advantage of 3D numerical simulations of seismic wave propagation 
 and data sensitivities to model parameters based on the adjoint method (i.
 e.\, Fr&eacute\;chet or adjoint kernels)\, which are elastic and transvers
 ely isotropic in the upper mantle and constructed using traveltimes of wav
 eforms only. To further improve the resolution of tomographic models and m
 ake use of full waveforms\, we need to better address the physics of the E
 arth's interior in inversions through appropriate parameterizations\, such
  as general anisotropy and anelasticity. We first addressed azimuthal anis
 otropy in the upper mantle in addition to the transverse isotropy\, as the
 re is strong evidence that Earth's upper mantle shows azimuthal anisotropy
 . On the other hand\, there is no consensus on the current mantle attenuat
 ion models\, which affect not only amplitudes but also the phase of wavefo
 rms due to physical dispersion. To this end\, we have explored the simulta
 neous inversion of elastic and anelastic parameters by performing a set of
  3D global synthetic full-waveform inversion (using both phase and amplitu
 de information) tests with a realistic global source-receiver distribution
  to assess the trade-off between elastic and anelastic parameters and the 
 expected resolution in global adjoint models. We will discuss our current 
 results\, recent efforts to address computational and data challenges\, an
 d future directions in the context of global seismology. We perform our cu
 rrent simulations on Texas Advanced Computing Center's Frontera system.
LOCATION:Seminar Room 1\, Newton Institute
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